HEI upgrade problems
Thread Starter
Intermediate
Joined: Jun 2010
Posts: 26
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From: Ball Ground Georgia
HEI upgrade problems
I have a 71 Corvette with a 350 engine. I just replaced the distributor with an HEI with new plug wires and plugs. I set the plug gap to .045. The problem is the car won't start now. I have triple checked the plug wires to make sure they are correct. I wired the power to the pink at the fuse block as per several post on this site. I checked the voltage on the lead to the HEI and with the key on it shows 12V but when cranking it drops to 9V. Is this correct? What else could be wrong?
Race Director
Joined: Sep 2004
Posts: 11,874
Likes: 263
From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
sounds like your ballast resistor circut is still in place. let me think about this so i dont steer you wrong....
on the old distributors they used a ballast resistor to reduce the voltage when the car was running to 9v for the coil. it would crank with 12 volts going to coil then when the starter disengaged it went back to 9 volts....i dont think you should be using the ballast resistor circuit at all with this set up...let me think about this
is the power coming to the HEI from the fuse block only?
HEI systems will work on very low voltage.....put an inductive ti ming light on the spark pug wires and determine if you have a spark?
it may be a bad module or even something is grounding out
on the old distributors they used a ballast resistor to reduce the voltage when the car was running to 9v for the coil. it would crank with 12 volts going to coil then when the starter disengaged it went back to 9 volts....i dont think you should be using the ballast resistor circuit at all with this set up...let me think about this
is the power coming to the HEI from the fuse block only?
HEI systems will work on very low voltage.....put an inductive ti ming light on the spark pug wires and determine if you have a spark?
it may be a bad module or even something is grounding out
Last edited by bobs77vet; Feb 28, 2011 at 02:43 PM.
Thread Starter
Intermediate
Joined: Jun 2010
Posts: 26
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From: Ball Ground Georgia
Resistance wire
sounds like your ballast resistor circut is still in place. let me think about this so i dont steer you wrong....
on the old distributors they used a ballast resistor to reduce the voltage when the car was running to 9v for the coil. it would crank with 12 volts going to coil then when the starter disengaged it went back to 9 volts....i dont think you should be using the ballast resistor circuit at all with this set up...let me think about this
is the power coming to the HEI from the fuse block only?
on the old distributors they used a ballast resistor to reduce the voltage when the car was running to 9v for the coil. it would crank with 12 volts going to coil then when the starter disengaged it went back to 9 volts....i dont think you should be using the ballast resistor circuit at all with this set up...let me think about this
is the power coming to the HEI from the fuse block only?
I have spark because at times it will backfire through the carburetor. Is 9V enough power to give a good spark with a plug gap of .045?
Last edited by ukwildcat53; Feb 28, 2011 at 02:47 PM. Reason: Addition to post
Race Director
Joined: Sep 2004
Posts: 11,874
Likes: 263
From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
ballast resistor or resistance wire it does the same thing...so thats not in play.....while a car is cranking voltage will drop thats why they created the ballast resistor stuff to begin with. i dont think that the lowe voltage is causing your problem....you either have something grounding out in the HEI preventing the spark from leaving or your module is bad. let me think how you can test that....first check to see if you have a spark at the plugs. this will confirm where the problem is
Race Director
Joined: Sep 2004
Posts: 11,874
Likes: 263
From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
ok you have a spark good....i think 9 volts would make it run.....if you are not sure run a jumper straight from your battery to the HEI power lead by passing the ignition switch.....if you have spark and it back fires how do you know its not in 180* out or the timing is way off?
i think your issue is timing not voltage
i think your issue is timing not voltage
Instructor
Joined: Jul 2006
Posts: 208
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From: Hamden CT
St. Jude Donor '12
Not sure about the 'pink at the fuse block' you speak of. I ran my HEI wire to the IGN terminal directly on the fuse block with a female quick disconnect type connector on the end of the wire. This drop to 9V from 12V doesn't sound good at all. Is it a coil-in-cap type dizzy or an external coil type?
Don't take this the wrong way but are you sure you didn't put the distributor back in 180 degrees off?
Don't take this the wrong way but are you sure you didn't put the distributor back in 180 degrees off?
Thread Starter
Intermediate
Joined: Jun 2010
Posts: 26
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From: Ball Ground Georgia
This is the first distributor I have ever replaced and I have read every article and post I could find about how to do it. I marked where the rotor was on the other distributor and lined up the rotor on the HEI to the same mark. The HEI has tach drive so that can only go one way. I traced all of the plug wires to the old distributor to make sure I knew exactly how to put them back. The HEI is coil in cap. You aren't going to hurt my feelings. I am learning under fire so question everything you want.
Race Director
Joined: Sep 2004
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From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
i bet your timimg is off....probably the easiset way to do this is to pull the valve cover and crank the engine by hand and follow through the TDC timing marks as you watch the valves open and close on number 1....when you hit TDC of the compression stroke leave it there...you can tell which valves are intake and exhaust by their relation to the exhaust manifold...the cycles are Intake, compression, power and exhaust.... you want the TDC mark right after the Intake valve closes..the plan is to align your rotor pointing to the number 1 spark tower and life is good.....to do this mark with a sharpie felt pen the #1 tower location on the distributor base remove the distribuotr cap and lift the distributor in and out and let it "walk" the rotor forward until it is pointing at number 1 spark tower mark.....also make sure that when you do this the vacumm can is in the middle of the adjusting area. this will get you in the right area for running and set final timing from there. and if you run out of adjusting room you know how to "walk" the distributor rotor to where you want it.
Last edited by bobs77vet; Feb 28, 2011 at 03:25 PM.
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Thread Starter
Intermediate
Joined: Jun 2010
Posts: 26
Likes: 0
From: Ball Ground Georgia
I have moved the distributor all over the place in small increments and it has never attempted to start but it does backfire through the carburetor at times.
Thread Starter
Intermediate
Joined: Jun 2010
Posts: 26
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From: Ball Ground Georgia
i bet your timimg is off....probably the easiset way to do this is to pull the valve cover and crank the engine by hand and follow through the TDC timing marks as you watch the valves open and close on number 1....when you hit TDC of the compression stroke leave it there...you can tell which valves are intake and exhaust by their relation to the exhaust manifold...the cycles are Intake, compression, power and exhaust.... you want the TDC mark right after the Intake valve closes..the plan is to align your rotor pointing to the number 1 spark tower and life is good.....to do this mark with a sharpie felt pen the #1 tower location on the distributor base remove the distribuotr cap and lift the distributor in and out and let it "walk" the rotor forward until it is pointing at number 1 spark tower mark.....also make sure that when you do this the vacumm can is in the middle of the adjusting area. this will get you in the right area for running and set final timing from there. and if you run out of adjusting room you know how to "walk" the distributor rotor to where you want it.
Pro
Joined: Jan 2010
Posts: 533
Likes: 18
From: Boca Raton Florida
When you pulled out the old distributor, did you notice that the rotor turned slightly on the way out? If you put the new distributor in without it doing that same turn, you are one or two teeth off on the distributor gear, giving you the changed timing. Disconnect your tach drive and perhaps even take the bracket for the distributor shield off so you can rotate the distributor in either direction easily. Have someone crank the engine over and turn the distributor until the engine fires.
Once you have it running, you can do the distributor dance where you pull it out, turn it a little and drop it back in until you have the tach and vacuum advance positioned where you want them.
Once you have it running, you can do the distributor dance where you pull it out, turn it a little and drop it back in until you have the tach and vacuum advance positioned where you want them.
Thread Starter
Intermediate
Joined: Jun 2010
Posts: 26
Likes: 0
From: Ball Ground Georgia
When you pulled out the old distributor, did you notice that the rotor turned slightly on the way out? If you put the new distributor in without it doing that same turn, you are one or two teeth off on the distributor gear, giving you the changed timing. Disconnect your tach drive and perhaps even take the bracket for the distributor shield off so you can rotate the distributor in either direction easily. Have someone crank the engine over and turn the distributor until the engine fires.
Once you have it running, you can do the distributor dance where you pull it out, turn it a little and drop it back in until you have the tach and vacuum advance positioned where you want them.
Once you have it running, you can do the distributor dance where you pull it out, turn it a little and drop it back in until you have the tach and vacuum advance positioned where you want them.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,114
From: Crossville TN
Did you crank the engine at all in an effort to help the distributor engage with the oil pump drive shaft? If so, your timing is totally off and you need to get back to TDC [on the 'compression' cycle]. You will have to use a large/long screwdriver to rotate the oil pump drive shaft for aligning it with the distributor (which should have the rotor aligned with the #1 plug wire contact).
Burning Brakes
Joined: Aug 2006
Posts: 1,058
Likes: 27
From: Eastern North Carolina
Did you crank the engine at all in an effort to help the distributor engage with the oil pump drive shaft? If so, your timing is totally off and you need to get back to TDC [on the 'compression' cycle]. You will have to use a large/long screwdriver to rotate the oil pump drive shaft for aligning it with the distributor (which should have the rotor aligned with the #1 plug wire contact).
Thread Starter
Intermediate
Joined: Jun 2010
Posts: 26
Likes: 0
From: Ball Ground Georgia
Did you crank the engine at all in an effort to help the distributor engage with the oil pump drive shaft? If so, your timing is totally off and you need to get back to TDC [on the 'compression' cycle]. You will have to use a large/long screwdriver to rotate the oil pump drive shaft for aligning it with the distributor (which should have the rotor aligned with the #1 plug wire contact).
Race Director
Joined: Sep 2004
Posts: 11,874
Likes: 263
From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
ok lets do this another way......take an inductive timing light that has a dial back function and put it on different spark plug wires and crank the engine while looking for the index mark on the harmonic balancer move the dial back function and then skip a spark plug wire and go to the next one keep doing this unitl you see the index marker lined up with 0*.....compare this to the spark plug tower that is going to the number 1 cylinder.....if its not the same you have just seen how far off you are.... it is possible that the harmonic balancer has slipped but if you have timed the engine before using this index line we can assume that is not the issue......being 180* out of alignment is easy and everyone has done it.....it just means you hit TDC of the exhaust stroke insted of the compression stroke. rememember TDC and the index mark are for the TDC of the number 1 cylinder.
